The present invention pertains to processes for the utilization of cellulosic starch and protein-containing waste products such as bran from cereal and flour mills and broken pieces and crumbs of baked goods from bakeries by converting the starch therein into protein-containing nutriments and supplements for animal feeds that are richer in proteins and accordingly more valuable than the original waste products.
In the production of cereal products, large quantities of waste products are produced which are used almost exclusively for animal feeds that nonetheless have inferior nutritional value. Considerable quantities of such cellulosic starch and protein-containing waste products are produced, for example, in the production of baked goods such as biscuits and crackers in bakeries. Furthermore, such bran is also produced in the milling of flour and other cereals.
Processes are known for the conversion of starches and starch-like substances into protein-containing plants, such as yeast cells or solids. One such process, which is described in U.S. Pat. No. 3,105,799, consists in symbiotically cultivating in a substratum consisting essentially of potatoes or similar vegetable material containing starch with two microorganisms, namely, one which hydrolyzes starch, such as Endomycopsis fibuliger, and a sugar-fermenting yeast, and separating the yeast plants that were grown therein during the fermentation, which yeast plants can be used as a nutriment. Such waste products, however, also contain a substantial portion of highly valuable proteins which had heretofore been overlooked or ignored.
Processes have also been described for the recovery of proteins by ultrafiltration but such processes have been heretofore used chiefly in the dairy industry, for example, for recovery of proteins from milk, for example, in an apparatus such as is described in German published application No. 2,220,308.